Successful treatment of immune-related cystitis by Chai-Ling-Tang (Sairei-To) in a gastric carcinoma patient: Case report and literature review

Immune checkpoint inhibitors (ICIs) have changed the landscape of advanced cancer treatment. However, immune checkpoint inhibitors can trigger effector T cells against self-antigens as well as tumor antigens, resulting in immune-related toxicities in normal organs, referred to as immune-related adverse events (irAEs).A 56-year-old man with undifferentiated gastric carcinoma received sintilimab plus paclitaxel and tegafur therapy. After five cycles of treatment, the patient was referred to the hospital for sudden onset urinary frequency, micturition pain, and urinary incontinence. Cystoscopy revealed the entire bladder mucosa was red and edematous but there was no evidence of tumor. Oral administration of Chai-Ling-Tang (Sairei-To) alleviated lower urinary tract symptoms (LUTS). Histological analysis revealed numerous infiltrates of CD3-positive and CD8-positive cells into the urothelium but no atypia, indicating a diagnosis of immune-related cystitis. Interestingly, the urothelial epithelium infiltrated by lymphocytes and subepithelial inflammatory cells strongly expressed cell boundary PD-L1. The dose of Chai-Ling-Tang was maintained and stopped 2 months later without recurrence of LUTS. Since recovering from cystitis, the patient remains alive with no disease progression.This report shows that Chai-Ling-Tang is safe and effective for treating immune-related cystitis. The detailed mechanism of action requires further investigation.